/*
 * Copyright 2012-2017 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.springframework.boot.context.embedded;

import org.springframework.beans.BeansException;
import org.springframework.beans.factory.BeanFactory;
import org.springframework.beans.factory.BeanFactoryAware;
import org.springframework.beans.factory.ListableBeanFactory;
import org.springframework.beans.factory.config.BeanPostProcessor;
import org.springframework.core.annotation.AnnotationAwareOrderComparator;
import org.springframework.util.Assert;

import java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;
import java.util.List;

/**
 * {@link BeanPostProcessor} that applies all {@link EmbeddedServletContainerCustomizer}s
 * from the bean factory to {@link ConfigurableEmbeddedServletContainer} beans.
 *
 * @author Dave Syer
 * @author Phillip Webb
 * @author Stephane Nicoll
 */
public class EmbeddedServletContainerCustomizerBeanPostProcessor implements BeanPostProcessor, BeanFactoryAware
{

    private ListableBeanFactory beanFactory;

    private List<EmbeddedServletContainerCustomizer> customizers;

    @Override
    public void setBeanFactory(BeanFactory beanFactory)
    {
        Assert.isInstanceOf(ListableBeanFactory.class, beanFactory,
                            "EmbeddedServletContainerCustomizerBeanPostProcessor can only be used " +
                                    "with a ListableBeanFactory");
        this.beanFactory = (ListableBeanFactory) beanFactory;
    }

    /**
     * 初始化之前
     *
     * @param bean
     * @param beanName
     * @return
     * @throws BeansException
     */
    @Override
    public Object postProcessBeforeInitialization(Object bean, String beanName) throws BeansException
    {
        // todo 如果当前初始化的是一个ConfigurableEmbeddedServletContainer类型的组件
        if (bean instanceof ConfigurableEmbeddedServletContainer)
        {
            postProcessBeforeInitialization((ConfigurableEmbeddedServletContainer) bean);
        }
        return bean;
    }

    @Override
    public Object postProcessAfterInitialization(Object bean, String beanName) throws BeansException
    {
        return bean;
    }

    private void postProcessBeforeInitialization(ConfigurableEmbeddedServletContainer bean)
    {
        // 获取所有的定制器，调用每一个定制器的customize方法来给Servlet容器进行属性赋值；
        for (EmbeddedServletContainerCustomizer customizer : getCustomizers())
        {
            customizer.customize(bean);
        }
    }

    private Collection<EmbeddedServletContainerCustomizer> getCustomizers()
    {
        if (this.customizers == null)
        {
            // Look up does not include the parent context
            //从容器中获取所有这些类型的组件：EmbeddedServletContainerCustomizer
            //定制Servlet容器，给容器中可以添加一个EmbeddedServletContainerCustomizer类型的组件
            this.customizers = new ArrayList<EmbeddedServletContainerCustomizer>(
                    this.beanFactory.getBeansOfType(EmbeddedServletContainerCustomizer.class, false, false).values());
            Collections.sort(this.customizers, AnnotationAwareOrderComparator.INSTANCE);
            this.customizers = Collections.unmodifiableList(this.customizers);
        }
        return this.customizers;
    }

}
